What Did You Do Today 2019

[BazyleParticipant @bazyle]

Great day for EDMES. Signed agreement with Community Association for building our track. Of course this doesn't get it built so anyone in Devon with time on their hands is welcome to come along.

[Anthony KnightsParticipant @anthonyknights16741]

Today the tool chest I treated myself to, was delivered. I intend keeping it in the house to store all my valuable measuring equipment away from the damp of the garage/workshop.

[Anthony KnightsParticipant @anthonyknights16741]

Started cleaning some calipers and dividers I've had for years. Dunked them briefly in B&Q brick cleaner to remove traces of rust and other crap. All went well until these outside calipers were done. They had been soaking for about five minutes when PING ! The spring cracked across the top. Has anyone any theories why this happened?

[Anonymous]

Posted by Anthony Knights on 02/04/2019 09:49:21:

The spring cracked across the top. Has anyone any theories why this happened?

Brick cleaner contains hydrochloric acid. The acid will preferentially attack grain boundaries and/or pre-existing cracks. Once the acid starts to eat away material it creates a stress raiser; result is PING.

Andrew

[Anonymous]

Posted by Paul Lousick on 01/04/2019 07:30:42:

Additional colours were added with a Beugler striping tool held in the chuck.

Man, that's neat.

How are you getting on with the Beugler? I bought one some years ago, although I haven't actually used it yet. I've heard of mixed results; I suspect that the paint viscosity is critical?

Andrew

[GoCreateParticipant @gocreate]

Anthony

Could be hydrogen embrittlement, higher strength/hardness materials are more susceptible. I'm not an expert but basically the material absorbs hydrogen atoms which results in material becoming very susceptible to brittle failure and unable to sustain it's normal/design loads.

It can be cured buy heating the component over several hours at something like 200 deg but must be done very soon after the hydrogen embrittlement occurs, If not done in time then the heat treatment is not effective.

It's normal practice for High tensile components to have hydrogen enbrittlement prevention heat treatment done after various plating processes etc were the material may have absorbed hydrogen atoms.

Nigel

Edited By tractionengine42 on 02/04/2019 10:33:17

[SillyOldDufferModerator @sillyoldduffer]

Posted by tractionengine42 on 02/04/2019 10:32:17:

Anthony

Could be hydrogen embrittlement, higher strength/hardness materials are more susceptible.

Nigel

Edited By tractionengine42 on 02/04/2019 10:33:17

Could be, but I think Andrew's suggestion is more probable. I have a set of B&Q dividers and whilst they work they can't be described as high-quality. Not unlikely that the bow-spring was flawed from new or that it was damaged in use causing the force exerted by the spring to concentrate on a crack. Very likely the acid was the last straw: it opened the crack enough for it to propagate, and the spring destroyed itself by lever action.

Somewhere I've an interesting graph comparing the tensile strength of steel rods identical apart from finish. From memory a polished rod is about 10% stronger than an unfinished rod, and a super-fine rod is about 10% stronger again. The reason is that tiny surface imperfections can concentrate stress severely at a point, enough to cause local tearing, which further concentrates the stress. Obvious that cutting a sharp notch in a rod will weaken it, not so obvious that polishing improves them.

Polishing to increase strength isn't that common. I think because it's usually cheaper to use a bigger rod than to polish small ones that might get scratched.

Dave

[Ian S CParticipant @iansc]

Another thing with high carbon steel, don't use the electrolitic method of derusting , you get the same result as the hydrochloric acid.

Ian S C

[Anonymous]

Posted by SillyOldDuffer on 02/04/2019 11:05:37:

Polishing to increase strength isn't that common. I think because it's usually cheaper to use a bigger rod than to polish small ones that might get scratched.

Some highly stressed components, like aircraft landing gear, go thorugh a complex manufacturing process including heat treatment, shot peening, and plating with specified surface finishes to reduce the possibility of cracks. It can be embarassing when it goes pear shaped:

**LINK**

The first picture in the report sums it up, what can you say other than ooops!

Andrew

[JohnFParticipant @johnf59703]

Posted by SillyOldDuffer on 30/03/2019 18:10:17:

Posted by Baz on 30/03/2019 17:03:34:

Can you crimp or solder on about 1/2 of thin wall brass or copper tube to the end of the Bowden cable to stop the fraying?

Bit scary!

Big problem with using metal cable for strimming is the amount of energy stored in the spinning wire is proportional to its density and Steel is over 8 times heavier than Nylon. When a steel cord breaks it will have much higher striking power, whilst the fragments make more effective projectiles, travelling more than 8 times the distance of Nylon bits of the same size.

As the guard on a strimmer isn't as complete as a rotary motor, I'd be wary of using Bowden cable in one. It's a lot riskier than the plastic wire recommended in the manual.

Dave

Hi everyone who posted on this subject — as others have already said BE VERY WARY of substituting materials for the recommended string or plastic blades. Some years ago in south Cumbria there was an accident with a strimmer fitted with commercial metal blades [now banned I believe ] I cannot remember the details but two men were working together, the blade from the strimmer detached and killed the other man outright ! A freak accident maybe but better safe than sorry IMO !

As a matter of interest I use Oregon Duoline in my strimmer, it has some sort of reinforced core and lasted better than any of the standard nylon types I have used.

Be safe John

[SillyOldDufferModerator @sillyoldduffer]

Posted by Andrew Johnston on 02/04/2019 11:45:52:

Posted by SillyOldDuffer on 02/04/2019 11:05:37:

…

Some highly stressed components, like aircraft landing gear, go thorugh a complex manufacturing process including heat treatment, shot peening, and plating with specified surface finishes to reduce the possibility of cracks. It can be embarassing when it goes pear shaped:

**LINK**

The first picture in the report sums it up, what can you say other than ooops!

Andrew

What a fascinating read, thanks Andrew.

It's a shame they never found who dunnit, or why! (To save reading the full report, an aircraft wheel broke off at slow speed after a successful landing. The refurbished landing gear failed due to a stress concentration at a small area of damaged chrome plating, slight corrosion, and locally changed steel. The damage was due to application of a point source of heat, hot enough to change the steel, applied by an unidentified party for reasons unknown. I'd be looking for a chap who believes in 'H&S Gone Mad' who now remembers absolutely nothing about his role in refurbishing the part!)

The Smithsonian channel on Freeview is running an interesting series following the National Transportation Safety Board as they investigate air crashes in Alaska. More private aircraft in Alaska than any other US State, and – on average – one crashes every other day during the summer. I've become quite expert! Checking continuity, carburettor icing, monoxide poisoning, pilot error, stalls, log books, fuel starvation, overloading, balance, proving if the engine was running on impact, witness reports accurate or not, GPS evidence, and how to separate crash damage from root causes! Pilot error seems to be the main cause of crashes, mostly chaps getting caught out rather than stupidity.

One thing I'd like to know more about. Early on the NTSB delicately ask the grieving relatives if the plane is insured. If not, it appears the family are liable for bills arising from recovering the wreck for investigation. Not clear if they could choose to leave the plane uninvestigated in the wilderness, or if recovery is mandatory and the estate has to cough up. Not nice when there's been a fatality.

Dave

[Joseph Noci 1Participant @josephnoci1]

Spent today ( and the last 14 days..) repairing my Solar heating system…

Input heat exchanger

Output heat exchanger

I have evacuated glass tube water heaters on the house roof, heating via a copper pipe heat exchanger the water in a 45000 litre underground storage tank. That thermal store in turn heats the water that is pumped through underfloor piping in the house flooring. This takes place by means of yet another heat exchanger in the floor heating loop. The water in the tank is isolated from both the solar heaters and the floor heating system.

The heat exchangers are four spirals of soft drawn copper tubing, 20mm OD , 0.9mm wall, wound in a spiral and connected in parallel. Both exchangers were riddled with tiny pinholes and so leaked. This after 11 years. The water in the tank reaches temperatures of 45 to 50 deg C max. The water PH has been between 6.9 and 7.3. Both copper coils are electrically isolated from the rest of the piping and systems – a heavy section of PEX oxygen barriered pipe connects each exchanger to the respective hot in and cold outlets, so no electrolytic action. The tank is a 8mm wall thickness Roto-Molded Polyprop unit, wrapped with wooden slats ( like a wine barrel) to keep it in shape when full of hot water. It is fine, but the copper piping .. The internals of the copper pipe is in good nick – the walls are evenly coated with a very fine brown/red cuprous oxide and no sign of corrosion or green anywhere within.

So, drain the tank, hauls out the old piping, get new pipes from SA, wind the spirals, fit connections, do the pressure tests, wash out all flux, and down the hole it all goes tomorrow!

Next Time I will get rid of half the problem and move to PV panels heating the thermal store with heating elements!

Heavy work..Each exchanger weighs around 45kg..

Joe

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, today I did a bit of a kiddies job by making 16 2BA X 1/2" (12.5mm) O/D brass washers from 1.5mm thick sheet brass. Firsly I marked them out with a fine ink pen.

Then using my mini mill and the DRO's, I piloted them with a centre drill and drilled them 4.9mm, in batches of four across.

Then separated them all by hacksawing and deburred the holes and cut edges on both sides.

I then turned down a piece of 12mm O/D bright mild steel for about 40mm long to fit the holes snugly and threaded it 5mm long enough to clamp all the washers tightly together and turned them to size.

Each one then had the corners broke using a small file while holding them in the lathe with a bit of threaded hex and screw which I found in my box of rescued screws.

16 finished brass washers, the odd one at the top is the commercially made one that I used as a pattern.

This is what they have been made for. They look quite dashing with my new brass cheese head screws, which arrived in the post this morning. The red felts came off old piano keys, which act as a buffer between the washers and the plastic tweeter.

Regards Nick.

[Nigel Graham 2Participant @nigelgraham2]

They look good, Nick!

I spent more time trying to fit the DRO encoder to the milling-machine. Machine-DRO's instructions recommend keeping the sensor and cable out of the reach of swarf and cutting-fluid. The magnetic strip and encoder, yes, but the cable? Although in a metal hose? Bit tricky that.

After searching the B&Q< Screwfix and Tool Station catalogues without success, for plastic hose of >21mm bore, I remembered one of my local sources of engineering materials is the camp-site shop. Oh, I do buy camping requisites there too.

Sure enough, I came home with 10 metres of very flexible, corrugated water-hose. It's actually intended for caravan sink wastes. The shop staff were intrigued by my intention, and my testing the diameter and length with one of the encoders and its very long lead.

Made new mounting-block for the sensor. Still not happy with how it came out… At least I have identified why not, and can carry out more discerning measurements, a bit of lateral thinking, and try v.3.

Thence to the model-engineering club's meeting-room for an interesting talk by one member, on his experiences of working on refuelling Royal Naval nuclear-powered submarines.

[Michael GilliganParticipant @michaelgilligan61133]

Just spotted something I never expected to see for sale by RDG

**LINK**

http://www.ebay.co.uk/itm/RDG-TOOLS-SWITZERLAND-SLIMLINE-ROTARY-TABLE-SOCIETE-GENEVOISE-200MM-DIAMETER/352632794919

… I dare not buy another Rotary Table : But someone could grab a bargain.

MichaelG.

[martin perman 1Participant @martinperman1]

Next Saturday is the Cotswold Oil Engine and Preservation Society Bring and Buy sale at Oakley Airfield, Worminghall, Bucks HP18 9PH which I attend twice a year to find parts for my stationary engines, this year much to my wifes pleasure I've decided to part with two of my "projects". I've been doing a lot of machining for friends lately and these engines stand next to my lathe and I've had one of them sitting in the garage for fourteen years asleep so i've decided it needs to go to a new home so my good friend Peter came around this morning to help me re-arrange my garage to get the engines out and then load them into my trailer, no mean feat as these engines are quite heavy, more than two men can lift, three would struggle.

Having got the engines out of the garage we then rachet strapped the engines to the basic trolleys they sat on and winched them into the trailer, I have a 2000 kg winch and even though my biggest engine doesn't weigh that much it cerainly made the winch grunt pulling it up the ramps but we are now loaded up and ready for the sale, with all of the other stuff, including a verticle band saw I reckon I have just over a ton in the trailer which will give the car a work out as well.

Martin P

[not done it yetParticipant @notdoneityet]

Go on Martin, tell us more! What are you offering for sale? I might even trundle over to Somerton and then attend with my brother… Nothing as big as a CS, then?

[martin perman 1Participant @martinperman1]

I'm offering a 2hp Lister D Bruston Generating set, 110 volt 9 amps, its complete not seized but needs work to get back to running order, a tank cooled Lister B with no magneto, but complete and ready to run and a vertical band saw on a stand with blades, it does run but needs the motor looking at, plus a load of Lister D spares and some large G clamps.

Martin P

[AdrianRParticipant @adrianr18614]

Bought a Warco BH600 lathe and Engineer Tool Room BMD-16 mill today. Perfect weather and despite my worries the moving it went very smoothly.

[Martin ConnellyParticipant @martinconnelly55370]

Helped my wife's uncle sell his lathe today. 

Martin C 

Edited By Martin Connelly on 08/04/2019 20:42:58

[AdrianRParticipant @adrianr18614]

Wow what a coincidence, that looks just like the one I bought

[Bill PhinnParticipant @billphinn90025]

Posted by Jim Young 2 on 31/03/2019 17:58:10:

Re brittle strimmer cord, I moaned at my local mower repair place about the short life of coils of strimmer cord. They recommended storing in an ice cream tub in water. Seems to help but of course it soon dries out when left on the strimmer.

Jim, I've been using Stihl strimmer line for the last 38 years, and never had a problem with it even when used with my relatively powerful Stihl KM130 brush cutter. I've never had to keep it moist or resort to any other method to reduce brittleness, because it really isn't brittle unless I make the mistake of trying to cut excessively tough material with it such as thick brambles, which, as the manufacturer advises, I would normally use a (Stihl) metal blade to cut.

Just make sure you buy the right diameter line for whatever cutting head you're using. I use 2.4mm cord (orange coloured) but you may need a thinner one. Your manual should say.

[martin perman 1Participant @martinperman1]

Having removed two engines from my garage ready for sale this weekend I've spent the last two days building a new bench in the space they took up, I've used 4" x 2" for the main frame but couldn't remember what sizes of ply wood for the bench top there were so I went and spoke to a neighbour who builds Bespoke kitchens and he offered me a 3 metre x 600 mm x 50 mm worktop he had lying around FOC, it will have a steel top when its finished so we picked it up to take over to my house, I struggled to carry my end, so put it down for a moment where upon my neighbour, 30 years my junior, picked it up stuck it on his shoulder and carried it to my yard, oh to be young again.

Martin P

[Swarf, Mostly!Participant @swarfmostly]

Posted by martin perman on 11/04/2019 18:39:27:

SNIP!

… I struggled to carry my end, so put it down for a moment where upon my neighbour, 30 years my junior, picked it up stuck it on his shoulder and carried it to my yard, oh to be young again.

Martin P

My stepson did something similar with a railway sleeper (actually, five * railway sleepers! ). Five years later, he had a spell in hospital for neck surgery. Might just be a coincidence?

* One at a time.

Best regards,

Swarf, Mostly!

[Chris BarryParticipant @chrisbarry]

Qualified on a new type of traction this week, class 68 diesel, and am making good progress on a 5c collet adapter for my Harrison 140.

Chris

[Author]

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